Java programming

short a = 0x55ff;

short b = 0x00ff;

System.out.printf(%08x , a & b);

System.out.printf(%08x , a | b);

System.out.printf(%08x , a ^ b);

System.out.printf(%08x , ~a);

//output

000000ff

000055ff

00005500

ffffaa00

*Can you tell me how to transfer to 8 hexadecimal digits??

*Can you please explain me in detail?

Thanks.